Filaments

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The Chinese University of Hong Kong *

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3152

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Biology

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Nov 24, 2024

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NOTES 382 OSMOSIS.ORG ( PATHOLOGY & CAVSES ) = Gram @ slender bacteria with @ branches (atypical lung disease organisms, capable of affecting any body organ = Atypical organisms — indolent disease — insidious growth — severe disease RISK FACTORS = [mmunodeficiency = Corticosteroid use — iatrogenic immunosuppression ( SIGNS & SYMPTOMS = Cough, dyspnea = [ndolent course = Common in fever’'s absence = Other symptoms = Dependent on organ systems affected by organism \—/ ( DIAGNOSIS ) DIAGNOSTIC IMAGING Chest X-ray = Localized alveolar infiltrate = Homogeneous, non-segmental, cavitary appearance GENERALLY, WHAT ARE THEY? LAB RESULTS = Tissue biopsy — histological OTHER DIAGNOSTICS Physical examination = Pulmonary examination s Auscultation: rhonchi (crackles), | breath sounds = Palpation: | tactile fremitus o Percussive dullness ¢ TREATMENT ) MEDICATIONS = Antibiotics SURGERY = Resection = Medication non-responsive = [ arge infections — significant dysfunction

Chapter 71 Filaments ACTINOMYCES ISRAELI osms.it/actinomyces-israelii ( PATHOLOGY & CAUSES ) Microbe characteristics = @ Gram stain = Shape = Filamentous, non-spore-forming, pleomorphic bacilli = Metabolism = Catalase negative, anaerobic/ microanaerobic bacilli = Types a 21 species found in humans s Actinomyces israelii most common = Locations = Normal mouth (by two years old), gastrointestinal (Gl) tract, female genitourinary tract flora PATHOLOGY » Uncommon infection source » Mucosal membrane violated — indolent, invasive disease = Commonly co-occurs with another pathogen — micro-O, Actinomyces environment = Can burrow through soft tissue, bone — small abscesses, drainage tracts = Abscesses: yellow sulfur-containing granules in granulomatous reactive material setting (bacteria found in microfilament tangles, surrounded by neutrophils) TYPES Cervicofacial = Osteomyelitis of mandible/maxilla = Resident flora in periodontal pockets, carious teeth, dental plaque, tonsillar crypts Thoracic = Pulmonary — pneumonia = Oropharyngeal content aspiration — bacterial alveoli seeding — immune response, bacterial growth — pneumonia Abdominal & pelvic = Gastrointestinal — appendicitis = Preceding colonic mucosa perforation — unrecognized — months—year course — symptomatic infection = Pelvic — female genitourinary infections = Complicated abortions, infected intrauterine devices (IUDs), endometritis, tubo-ovarian abscess (TOA) RISK FACTORS = Chronic granulomatous disease Cervicofacial = Chronic tonsillitis, dental decay, periodontal disease, mastoiditis, otitis media Thoracic = Aspiration history COMPLICATIONS Cervicofacial = Deep neck tissue infection — retropharyngeal space — mediastinitis = Meningitis — if sinus tracts to posterior neck, spinal cord Thoracic = Pneumonitis Abdominal & pelvic = Gastrointestinal = Peritoneal, hepatic, pelvic infectious spread OSMOSIS.ORG 383

( SIGNS & SYMPTOMS ) Cervicofacial = Lumpy jaw = Usually in fever's/other infectious signs’ absence = Progression — oral mucosa, trismus sinus tract draining Thoracic = Fever, cough > three day duration = Auscultation = Rhonchi s | breath sounds = Palpation = | tactile fremitus = Percussive dullness Abdominal & pelvic = Gastrointestinal — appendicitis = Asymptomatic colonic mucosa (micro) perforation — months—years prodrome — symptomatic appendicitis = Nonspecific prodrome: chronic fever, weight loss, diarrhea, constipation, night sweats = Appendicitis: nausea, vomiting, anorexia = Pelvic — female genitourinary infections s Painful abdominal, cervical examination = Purulent vaginal discharge ( DIAGNOSIS ) DIAGNOSTIC IMAGING Chest X-ray = Thoracic o Localized alveolar infiltrate: homogeneous; non-segmental, cavitary appearance; can extend past fissure lines — into chest wall Barium enema = Abdominal, pelvic = Luminal narrowing, fistualization, extrinsic compression 384 OSMOSIS.ORG CT scan = Abdominal, pelvic = Disrupted tissue planes Colonoscopy = Abdominal, pelvic = Normal/thickened mucosal appearance, colitis, ulceration, nodular lesion, button- like appendiceal orifice elevation Bedside ultrasound = Abdominal, pelvic o TOA evaluation LAB RESULTS = Cervicofacial = Monoclonal antibody staining = Polymerase chain reaction (PCR) of 16S rRNA Cultures (needle aspiration) = Cervicofacial = Histology: granulation tissues with neutrophils, foamy macrophages, lymphocytes, plasma cells (with surrounding fibrosis) = Abdominal, pelvic = Histology: granulation tissue surrounding oval, eosinophilic zones Figure 711 Sulphur granules formed by Actinomyces organismes.

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OTHER DIAGNOSTICS History = Thoracic = May have community-acquired pneumonia diagnosis, treatment (without relief within 3-5 days) Physical examination = Cervicofacial = Lymphatic examination = Thoracic = Pulmonary examination Chapter 71 Filaments ( TREATMENT ) MEDICATIONS = Antibiotics = Prolonged (weeks—months) penicillin V (oral)/penicillin G (intravenous) = Amoxicillin (alternative) SURGERY = Necrotic disease/especially large abscess formation cases NOCARDIA —osms.i{/nocardia— ( PATHOLOGY & CAVSES ) = Microbe characteristics = @ Gram stain = Shape = Filamentous, branch-forming, bacillus = Branches — beaded appearance (delicate nature of stain — cocci/bacilli fragmentation) = Metabolism = Aerobic, catalase @, urease @ = Types = > 80 species = Around 30 disease-causing in humans = Locations = Saprophyte (organic pathogen) — found in soil, house dust, water (fresh/salt), bathing pools PATHOLOGY = Direct tissue inoculation = Saprophyte — aerosolization common (T 1 pulmonary infections) = Soil/water contamination (contaminated food — Gl disease, skin trauma — cutaneous disease, eye trauma — ocular disease) = Facultative intracellular organism — requires innate host defense mechanisms = Inhalation entry: deficient/ineffective mucociliary clearance, host response — bronchopulmonary disease = Skin trauma entry: deficient keratinized skin barrier — local subcutaneous infection; deficient keratinized cornea — ocular infection = Rapid filamentous growth — | phagocytic clearing s Phagocytosed — | lysosomal destruction (phagocyte-lysosome fusion inhibition; catalase, dismutase production — | reactive oxygen species — pathogen survival) TYPES Pneumonia = Nocardia asteroides (common pathogen) = > 243 of total disease = Progression = Empyema, pericardial effusion Primary cutaneous infections = Nocardia brasiliensis (common pathogen) = Cellulitis, ulcers, pyoderma, myocetma OSMOSIS.ORG 385

386 OSMOSIS.ORG = Progression = Abscess/nodular development, lymphangitis RISK FACTORS = | mucociliary clearance = Cystic fibrosis, asthma, bronchiectasis = [mmunosuppression = [atrogenic (most commonly corticosteroid use); lymphoreticular malignancy; chronic obstructive pulmonary disease; chronic granulomatous disease; dysgammaglobulinemia; HIV infection; bone marrow, organ transplant COMPLICATIONS = Organ dissemination = Pulmonary infection — hematogenous spread (commonly) = Most common: central nervous system (meningitis, cerebral abscess) = Pulmonary = Empyema, pericardial effusion = Cutaneous = Lymphanagitis = Ocular = Endophthalmitis (ocular infection) ( SIGNS & SYMPTOMS ) Pneumonia = Acute, subacute, chronic suppurative course = Symptoms may also relapse/remit = Cough, dyspnea common = Anorexia, weight-loss (uncommon) = Hemoptysis (cavitary disease) = Rhonchi (crackles) = | breath sounds, tactile fremitus, +/- egophony Local cutaneous infection = Local erythema, warmth, +/- ulceration, nodular growth Neurologic infection = Meningismus, fever, rigors, seizure ( DIAGNOSIS ) DIAGNOSTIC IMAGING Chest X-ray = Pulmonary = Homogeneous, non-segmental, cavitary alveolar infiltrate Brain MRI = Neurologic =1 T1 imaging intensity — 1 enhancement (gadolinium) LAB RESULTS = Tissue biopsy: histology (acid fast stain) = Gram @, branching, beaded filamentous growth ( TREATMENT ) MEDICATIONS Antibiotic monotherapy = Mild/moderate disease = 3—-6 months treatment duration = Sulfonamides — trimethoprim- sulfamethoxazole (TMP-SMX) = Linezolid = Nocardia 100% sensitive = Limited treatment duration (2-3 weeks) — ineffective monotherapy for complete therapy duration Antibiotic multi-agent therapy = Severe disease = Up to 6-12 months treatment duration = Agents = TMP-SMX + amikacin/carbapenem/ linezolid = Commonly for progressive disease in immunosuppressed individuals/oulmonary, disseminated disease Prevention & vaccine = Daily, full-strength TMP-SMX — secondary prophylaxis = P.jirovecii TMP-SMX prophylaxis (3x/week) — ineffective

SURGERY = Indicated for = Antibiotic-resistant, large cutaneous/ cerebral abscess (craniotomy/aspiration effective) = Empyemas, large fluid collections = Pulmonary nocardiosis — pericarditis (fatal if not performed) Chapter 71 Filaments OSMOSIS.ORG 387

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